[358ec13] | 1 | /*
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| 2 | * Copyright (c) 2007 Vojtech Mencl
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup genericadt
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| 30 | * @{
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| 31 | */
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| 32 |
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| 33 | /**
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| 34 | * @file
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| 35 | * @brief AVL tree implementation.
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| 36 | *
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| 37 | * This file implements AVL tree type and operations.
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| 38 | *
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| 39 | * Implemented AVL tree has the following properties:
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| 40 | * @li It is a binary search tree with non-unique keys.
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| 41 | * @li Difference of heights of the left and the right subtree of every node is
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| 42 | * one at maximum.
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| 43 | *
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| 44 | * Every node has a pointer to its parent which allows insertion of multiple
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| 45 | * identical keys into the tree.
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[ae318d3] | 46 | *
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[358ec13] | 47 | * Be careful when using this tree because of the base atribute which is added
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| 48 | * to every inserted node key. There is no rule in which order nodes with the
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| 49 | * same key are visited.
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| 50 | */
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| 51 |
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| 52 | #include <adt/avl.h>
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[63e27ef] | 53 | #include <assert.h>
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[358ec13] | 54 |
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| 55 | #define LEFT 0
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| 56 | #define RIGHT 1
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| 57 |
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| 58 | /** Search for the first occurence of the given key in an AVL tree.
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| 59 | *
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| 60 | * @param t AVL tree.
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| 61 | * @param key Key to be searched.
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| 62 | *
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| 63 | * @return Pointer to a node or NULL if there is no such key.
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| 64 | */
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[d1e9321] | 65 | avltree_node_t *avltree_search(avltree_t *t, avltree_key_t key)
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[358ec13] | 66 | {
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| 67 | avltree_node_t *p;
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[a35b458] | 68 |
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[358ec13] | 69 | /*
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| 70 | * Iteratively descend to the leaf that can contain the searched key.
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| 71 | */
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| 72 | p = t->root;
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| 73 | while (p != NULL) {
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| 74 | if (p->key > key)
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| 75 | p = p->lft;
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| 76 | else if (p->key < key)
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| 77 | p = p->rgt;
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[1b20da0] | 78 | else
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[358ec13] | 79 | return p;
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| 80 | }
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| 81 | return NULL;
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| 82 | }
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| 83 |
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| 84 |
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| 85 | /** Find the node with the smallest key in an AVL tree.
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| 86 | *
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| 87 | * @param t AVL tree.
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| 88 | *
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| 89 | * @return Pointer to a node or NULL if there is no node in the tree.
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| 90 | */
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| 91 | avltree_node_t *avltree_find_min(avltree_t *t)
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| 92 | {
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| 93 | avltree_node_t *p = t->root;
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[a35b458] | 94 |
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[358ec13] | 95 | /*
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| 96 | * Check whether the tree is empty.
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| 97 | */
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| 98 | if (!p)
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| 99 | return NULL;
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[a35b458] | 100 |
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[358ec13] | 101 | /*
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| 102 | * Iteratively descend to the leftmost leaf in the tree.
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| 103 | */
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[1b20da0] | 104 | while (p->lft != NULL)
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[358ec13] | 105 | p = p->lft;
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[a35b458] | 106 |
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[358ec13] | 107 | return p;
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| 108 | }
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| 109 |
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[83a5cba] | 110 | #define REBALANCE_INSERT_XX(DIR1, DIR2) \
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| 111 | top->DIR1 = par->DIR2; \
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| 112 | if (top->DIR1 != NULL) \
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| 113 | top->DIR1->par = top; \
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| 114 | par->par = top->par; \
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| 115 | top->par = par; \
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| 116 | par->DIR2 = top; \
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| 117 | par->balance = 0; \
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| 118 | top->balance = 0; \
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| 119 | *dpc = par;
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| 120 |
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| 121 | #define REBALANCE_INSERT_LL() REBALANCE_INSERT_XX(lft, rgt)
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| 122 | #define REBALANCE_INSERT_RR() REBALANCE_INSERT_XX(rgt, lft)
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| 123 |
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| 124 | #define REBALANCE_INSERT_XY(DIR1, DIR2, SGN) \
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| 125 | gpa = par->DIR2; \
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| 126 | par->DIR2 = gpa->DIR1; \
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| 127 | if (gpa->DIR1 != NULL) \
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| 128 | gpa->DIR1->par = par; \
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| 129 | gpa->DIR1 = par; \
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| 130 | par->par = gpa; \
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| 131 | top->DIR1 = gpa->DIR2; \
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| 132 | if (gpa->DIR2 != NULL) \
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| 133 | gpa->DIR2->par = top; \
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| 134 | gpa->DIR2 = top; \
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| 135 | gpa->par = top->par; \
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| 136 | top->par = gpa; \
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| 137 | \
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| 138 | if (gpa->balance == -1 * SGN) { \
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| 139 | par->balance = 0; \
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| 140 | top->balance = 1 * SGN; \
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| 141 | } else if (gpa->balance == 0) { \
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| 142 | par->balance = 0; \
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| 143 | top->balance = 0; \
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| 144 | } else { \
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| 145 | par->balance = -1 * SGN; \
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| 146 | top->balance = 0; \
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| 147 | } \
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| 148 | gpa->balance = 0; \
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| 149 | *dpc = gpa;
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| 150 |
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| 151 | #define REBALANCE_INSERT_LR() REBALANCE_INSERT_XY(lft, rgt, 1)
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| 152 | #define REBALANCE_INSERT_RL() REBALANCE_INSERT_XY(rgt, lft, -1)
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[a35b458] | 153 |
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[358ec13] | 154 | /** Insert new node into AVL tree.
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| 155 | *
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| 156 | * @param t AVL tree.
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| 157 | * @param newnode New node to be inserted.
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[1b20da0] | 158 | */
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[358ec13] | 159 | void avltree_insert(avltree_t *t, avltree_node_t *newnode)
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[1b20da0] | 160 | {
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| 161 | avltree_node_t *par;
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[358ec13] | 162 | avltree_node_t *gpa;
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| 163 | avltree_node_t *top;
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| 164 | avltree_node_t **dpc;
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[d1e9321] | 165 | avltree_key_t key;
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[358ec13] | 166 |
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[63e27ef] | 167 | assert(t);
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| 168 | assert(newnode);
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[358ec13] | 169 |
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| 170 | /*
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| 171 | * Creating absolute key.
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[1b20da0] | 172 | */
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[358ec13] | 173 | key = newnode->key + t->base;
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[a35b458] | 174 |
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[358ec13] | 175 | /*
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| 176 | * Iteratively descend to the leaf that can contain the new node.
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| 177 | * Last node with non-zero balance in the way to leaf is stored as top -
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| 178 | * it is a place of possible inbalance.
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| 179 | */
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| 180 | dpc = &t->root;
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| 181 | gpa = NULL;
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| 182 | top = t->root;
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| 183 | while ((par = (*dpc)) != NULL) {
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| 184 | if (par->balance != 0) {
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| 185 | top = par;
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| 186 | }
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| 187 | gpa = par;
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[3bacee1] | 188 | dpc = par->key > key ? &par->lft : &par->rgt;
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[358ec13] | 189 | }
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| 190 |
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| 191 | /*
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[83a5cba] | 192 | * Initialize the new node.
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[358ec13] | 193 | */
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| 194 | newnode->key = key;
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| 195 | newnode->lft = NULL;
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| 196 | newnode->rgt = NULL;
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| 197 | newnode->par = gpa;
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| 198 | newnode->balance = 0;
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| 199 |
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| 200 | /*
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| 201 | * Insert first node into the empty tree.
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| 202 | */
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| 203 | if (t->root == NULL) {
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| 204 | *dpc = newnode;
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| 205 | return;
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| 206 | }
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| 207 |
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| 208 | /*
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[83a5cba] | 209 | * Insert the new node into the previously found leaf position.
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[358ec13] | 210 | */
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| 211 | *dpc = newnode;
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| 212 |
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| 213 | /*
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| 214 | * If the tree contains one node - end.
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| 215 | */
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| 216 | if (top == NULL)
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| 217 | return;
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| 218 |
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| 219 | /*
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| 220 | * Store pointer of top's father which points to the node with
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| 221 | * potentially broken balance (top).
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| 222 | */
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| 223 | if (top->par == NULL) {
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| 224 | dpc = &t->root;
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[1b20da0] | 225 | } else {
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[358ec13] | 226 | if (top->par->lft == top)
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| 227 | dpc = &top->par->lft;
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| 228 | else
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| 229 | dpc = &top->par->rgt;
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| 230 | }
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| 231 |
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| 232 | /*
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| 233 | * Repair all balances on the way from top node to the newly inserted
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| 234 | * node.
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| 235 | */
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| 236 | par = top;
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| 237 | while (par != newnode) {
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| 238 | if (par->key > key) {
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| 239 | par->balance--;
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| 240 | par = par->lft;
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| 241 | } else {
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| 242 | par->balance++;
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| 243 | par = par->rgt;
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| 244 | }
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| 245 | }
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[a35b458] | 246 |
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[358ec13] | 247 | /*
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| 248 | * To balance the tree, we must check and balance top node.
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| 249 | */
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| 250 | if (top->balance == -2) {
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| 251 | par = top->lft;
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| 252 | if (par->balance == -1) {
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| 253 | /*
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| 254 | * LL rotation.
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| 255 | */
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[83a5cba] | 256 | REBALANCE_INSERT_LL();
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[1b20da0] | 257 | } else {
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[358ec13] | 258 | /*
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| 259 | * LR rotation.
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| 260 | */
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[63e27ef] | 261 | assert(par->balance == 1);
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[a35b458] | 262 |
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[83a5cba] | 263 | REBALANCE_INSERT_LR();
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[358ec13] | 264 | }
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[1b20da0] | 265 | } else if (top->balance == 2) {
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[358ec13] | 266 | par = top->rgt;
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| 267 | if (par->balance == 1) {
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| 268 | /*
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| 269 | * RR rotation.
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| 270 | */
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[83a5cba] | 271 | REBALANCE_INSERT_RR();
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[358ec13] | 272 | } else {
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| 273 | /*
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| 274 | * RL rotation.
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| 275 | */
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[63e27ef] | 276 | assert(par->balance == -1);
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[a35b458] | 277 |
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[83a5cba] | 278 | REBALANCE_INSERT_RL();
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[358ec13] | 279 | }
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[1b20da0] | 280 | } else {
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[358ec13] | 281 | /*
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| 282 | * Balance is not broken, insertion is finised.
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| 283 | */
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| 284 | return;
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| 285 | }
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| 286 |
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| 287 | }
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| 288 |
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| 289 | /** Repair the tree after reparenting node u.
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| 290 | *
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| 291 | * If node u has no parent, mark it as the root of the whole tree. Otherwise
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| 292 | * node v represents stale address of one of the children of node u's parent.
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| 293 | * Replace v with w as node u parent's child (for most uses, u and w will be the
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| 294 | * same).
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| 295 | *
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| 296 | * @param t AVL tree.
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| 297 | * @param u Node whose new parent has a stale child pointer.
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| 298 | * @param v Stale child of node u's new parent.
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| 299 | * @param w New child of node u's new parent.
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| 300 | * @param dir If not NULL, address of the variable where to store information
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| 301 | * about whether w replaced v in the left or the right subtree of
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| 302 | * u's new parent.
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| 303 | * @param ro Read only operation; do not modify any tree pointers. This is
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| 304 | * useful for tracking direction via the dir pointer.
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[1b20da0] | 305 | *
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[358ec13] | 306 | * @return Zero if w became the new root of the tree, otherwise return
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| 307 | * non-zero.
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| 308 | */
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| 309 | static int
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[18b6a88] | 310 | repair(avltree_t *t, avltree_node_t *u, avltree_node_t *v, avltree_node_t *w,
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[358ec13] | 311 | int *dir, int ro)
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| 312 | {
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| 313 | if (u->par == NULL) {
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| 314 | if (!ro)
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[1b20da0] | 315 | t->root = w;
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[358ec13] | 316 | return 0;
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[1b20da0] | 317 | } else {
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[358ec13] | 318 | if (u->par->lft == v) {
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| 319 | if (!ro)
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| 320 | u->par->lft = w;
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| 321 | if (dir)
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| 322 | *dir = LEFT;
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| 323 | } else {
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[63e27ef] | 324 | assert(u->par->rgt == v);
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[358ec13] | 325 | if (!ro)
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| 326 | u->par->rgt = w;
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| 327 | if (dir)
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| 328 | *dir = RIGHT;
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| 329 | }
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| 330 | }
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| 331 | return 1;
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| 332 | }
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| 333 |
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[83a5cba] | 334 | #define REBALANCE_DELETE(DIR1, DIR2, SIGN) \
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[358ec13] | 335 | if (cur->balance == -1 * SIGN) { \
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| 336 | par->balance = 0; \
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| 337 | gpa->balance = 1 * SIGN; \
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| 338 | if (gpa->DIR1) \
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| 339 | gpa->DIR1->par = gpa; \
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| 340 | par->DIR2->par = par; \
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| 341 | } else if (cur->balance == 0) { \
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| 342 | par->balance = 0; \
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| 343 | gpa->balance = 0; \
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| 344 | if (gpa->DIR1) \
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| 345 | gpa->DIR1->par = gpa; \
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| 346 | if (par->DIR2) \
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| 347 | par->DIR2->par = par; \
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| 348 | } else { \
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| 349 | par->balance = -1 * SIGN; \
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| 350 | gpa->balance = 0; \
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| 351 | if (par->DIR2) \
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| 352 | par->DIR2->par = par; \
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| 353 | gpa->DIR1->par = gpa; \
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| 354 | } \
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| 355 | cur->balance = 0;
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| 356 |
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[83a5cba] | 357 | #define REBALANCE_DELETE_LR() REBALANCE_DELETE(lft, rgt, 1)
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| 358 | #define REBALANCE_DELETE_RL() REBALANCE_DELETE(rgt, lft, -1)
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[358ec13] | 359 |
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| 360 | /** Delete a node from the AVL tree.
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| 361 | *
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| 362 | * Because multiple identical keys are allowed, the parent pointers are
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| 363 | * essential during deletion.
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[1b20da0] | 364 | *
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[358ec13] | 365 | * @param t AVL tree structure.
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| 366 | * @param node Address of the node which will be deleted.
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| 367 | */
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| 368 | void avltree_delete(avltree_t *t, avltree_node_t *node)
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| 369 | {
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| 370 | avltree_node_t *cur;
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| 371 | avltree_node_t *par;
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| 372 | avltree_node_t *gpa;
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| 373 | int dir;
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| 374 |
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[63e27ef] | 375 | assert(t);
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| 376 | assert(node);
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[a35b458] | 377 |
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[358ec13] | 378 | if (node->lft == NULL) {
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| 379 | if (node->rgt) {
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| 380 | /*
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[1b20da0] | 381 | * Replace the node with its only right son.
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[358ec13] | 382 | *
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| 383 | * Balance of the right son will be repaired in the
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| 384 | * balancing cycle.
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| 385 | */
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| 386 | cur = node->rgt;
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| 387 | cur->par = node->par;
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| 388 | gpa = cur;
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| 389 | dir = RIGHT;
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[1b20da0] | 390 | cur->balance = node->balance;
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[358ec13] | 391 | } else {
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| 392 | if (node->par == NULL) {
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| 393 | /*
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| 394 | * The tree has only one node - it will become
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| 395 | * an empty tree and the balancing can end.
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| 396 | */
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| 397 | t->root = NULL;
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| 398 | return;
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| 399 | }
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| 400 | /*
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| 401 | * The node has no child, it will be deleted with no
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| 402 | * substitution.
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| 403 | */
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| 404 | gpa = node->par;
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| 405 | cur = NULL;
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[3bacee1] | 406 | dir = (gpa->lft == node) ? LEFT : RIGHT;
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[358ec13] | 407 | }
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| 408 | } else {
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| 409 | /*
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| 410 | * The node has the left son. Find a node with the smallest key
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| 411 | * in the left subtree and replace the deleted node with that
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| 412 | * node.
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| 413 | */
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[84239b1] | 414 | cur = node->lft;
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| 415 | while (cur->rgt != NULL)
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| 416 | cur = cur->rgt;
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[358ec13] | 417 |
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| 418 | if (cur != node->lft) {
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| 419 | /*
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| 420 | * The rightmost node of the deleted node's left subtree
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| 421 | * was found. Replace the deleted node with this node.
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| 422 | * Cutting off of the found node has two cases that
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| 423 | * depend on its left son.
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[1b20da0] | 424 | */
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[358ec13] | 425 | if (cur->lft) {
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| 426 | /*
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| 427 | * The found node has a left son.
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| 428 | */
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| 429 | gpa = cur->lft;
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| 430 | gpa->par = cur->par;
|
---|
| 431 | dir = LEFT;
|
---|
[1b20da0] | 432 | gpa->balance = cur->balance;
|
---|
[358ec13] | 433 | } else {
|
---|
| 434 | dir = RIGHT;
|
---|
| 435 | gpa = cur->par;
|
---|
| 436 | }
|
---|
| 437 | cur->par->rgt = cur->lft;
|
---|
| 438 | cur->lft = node->lft;
|
---|
[1b20da0] | 439 | cur->lft->par = cur;
|
---|
| 440 | } else {
|
---|
[358ec13] | 441 | /*
|
---|
| 442 | * The left son of the node hasn't got a right son. The
|
---|
| 443 | * left son will take the deleted node's place.
|
---|
| 444 | */
|
---|
| 445 | dir = LEFT;
|
---|
[1b20da0] | 446 | gpa = cur;
|
---|
[358ec13] | 447 | }
|
---|
| 448 | if (node->rgt)
|
---|
[1b20da0] | 449 | node->rgt->par = cur;
|
---|
[358ec13] | 450 | cur->rgt = node->rgt;
|
---|
| 451 | cur->balance = node->balance;
|
---|
| 452 | cur->par = node->par;
|
---|
| 453 | }
|
---|
[a35b458] | 454 |
|
---|
[358ec13] | 455 | /*
|
---|
| 456 | * Repair the parent node's pointer which pointed previously to the
|
---|
| 457 | * deleted node.
|
---|
| 458 | */
|
---|
| 459 | (void) repair(t, node, node, cur, NULL, false);
|
---|
[a35b458] | 460 |
|
---|
[358ec13] | 461 | /*
|
---|
| 462 | * Repair cycle which repairs balances of nodes on the way from from the
|
---|
| 463 | * cut-off node up to the root.
|
---|
| 464 | */
|
---|
[84239b1] | 465 | while (true) {
|
---|
[358ec13] | 466 | if (dir == LEFT) {
|
---|
| 467 | /*
|
---|
| 468 | * Deletion was made in the left subtree.
|
---|
| 469 | */
|
---|
| 470 | gpa->balance++;
|
---|
| 471 | if (gpa->balance == 1) {
|
---|
| 472 | /*
|
---|
| 473 | * Stop balancing, the tree is balanced.
|
---|
| 474 | */
|
---|
| 475 | break;
|
---|
[1b20da0] | 476 | } else if (gpa->balance == 2) {
|
---|
[358ec13] | 477 | /*
|
---|
| 478 | * Bad balance, heights of left and right
|
---|
| 479 | * subtrees differ more than by one.
|
---|
| 480 | */
|
---|
| 481 | par = gpa->rgt;
|
---|
| 482 |
|
---|
| 483 | if (par->balance == -1) {
|
---|
| 484 | /*
|
---|
| 485 | * RL rotation.
|
---|
| 486 | */
|
---|
[a35b458] | 487 |
|
---|
[358ec13] | 488 | cur = par->lft;
|
---|
| 489 | par->lft = cur->rgt;
|
---|
| 490 | cur->rgt = par;
|
---|
| 491 | gpa->rgt = cur->lft;
|
---|
| 492 | cur->lft = gpa;
|
---|
[a35b458] | 493 |
|
---|
[358ec13] | 494 | /*
|
---|
| 495 | * Repair balances and paternity of
|
---|
| 496 | * children, depending on the balance
|
---|
| 497 | * factor of the grand child (cur).
|
---|
| 498 | */
|
---|
[83a5cba] | 499 | REBALANCE_DELETE_RL();
|
---|
[a35b458] | 500 |
|
---|
[358ec13] | 501 | /*
|
---|
| 502 | * Repair paternity.
|
---|
| 503 | */
|
---|
| 504 | cur->par = gpa->par;
|
---|
| 505 | gpa->par = cur;
|
---|
| 506 | par->par = cur;
|
---|
| 507 |
|
---|
| 508 | if (!repair(t, cur, gpa, cur, &dir,
|
---|
| 509 | false))
|
---|
| 510 | break;
|
---|
| 511 | gpa = cur->par;
|
---|
| 512 | } else {
|
---|
| 513 | /*
|
---|
| 514 | * RR rotation.
|
---|
| 515 | */
|
---|
[a35b458] | 516 |
|
---|
[358ec13] | 517 | gpa->rgt = par->lft;
|
---|
| 518 | if (par->lft)
|
---|
| 519 | par->lft->par = gpa;
|
---|
| 520 | par->lft = gpa;
|
---|
[a35b458] | 521 |
|
---|
[358ec13] | 522 | /*
|
---|
| 523 | * Repair paternity.
|
---|
| 524 | */
|
---|
| 525 | par->par = gpa->par;
|
---|
| 526 | gpa->par = par;
|
---|
[a35b458] | 527 |
|
---|
[358ec13] | 528 | if (par->balance == 0) {
|
---|
| 529 | /*
|
---|
| 530 | * The right child of the
|
---|
| 531 | * balanced node is balanced,
|
---|
| 532 | * after RR rotation is done,
|
---|
| 533 | * the whole tree will be
|
---|
| 534 | * balanced.
|
---|
| 535 | */
|
---|
| 536 | par->balance = -1;
|
---|
| 537 | gpa->balance = 1;
|
---|
| 538 |
|
---|
| 539 | (void) repair(t, par, gpa, par,
|
---|
| 540 | NULL, false);
|
---|
[1b20da0] | 541 | break;
|
---|
[358ec13] | 542 | } else {
|
---|
| 543 | par->balance = 0;
|
---|
| 544 | gpa->balance = 0;
|
---|
| 545 | if (!repair(t, par, gpa, par,
|
---|
| 546 | &dir, false))
|
---|
| 547 | break;
|
---|
| 548 | }
|
---|
| 549 | gpa = par->par;
|
---|
| 550 | }
|
---|
| 551 | } else {
|
---|
| 552 | /*
|
---|
| 553 | * Repair the pointer which pointed to the
|
---|
| 554 | * balanced node. If it was root then balancing
|
---|
| 555 | * is finished else continue with the next
|
---|
| 556 | * iteration (parent node).
|
---|
| 557 | */
|
---|
| 558 | if (!repair(t, gpa, gpa, NULL, &dir, true))
|
---|
| 559 | break;
|
---|
| 560 | gpa = gpa->par;
|
---|
| 561 | }
|
---|
[1b20da0] | 562 | } else {
|
---|
[358ec13] | 563 | /*
|
---|
| 564 | * Deletion was made in the right subtree.
|
---|
| 565 | */
|
---|
| 566 | gpa->balance--;
|
---|
| 567 | if (gpa->balance == -1) {
|
---|
| 568 | /*
|
---|
| 569 | * Stop balancing, the tree is balanced.
|
---|
| 570 | */
|
---|
| 571 | break;
|
---|
| 572 | } else if (gpa->balance == -2) {
|
---|
| 573 | /*
|
---|
| 574 | * Bad balance, heights of left and right
|
---|
| 575 | * subtrees differ more than by one.
|
---|
| 576 | */
|
---|
| 577 | par = gpa->lft;
|
---|
[a35b458] | 578 |
|
---|
[358ec13] | 579 | if (par->balance == 1) {
|
---|
| 580 | /*
|
---|
| 581 | * LR rotation.
|
---|
| 582 | */
|
---|
[a35b458] | 583 |
|
---|
[358ec13] | 584 | cur = par->rgt;
|
---|
| 585 | par->rgt = cur->lft;
|
---|
| 586 | cur->lft = par;
|
---|
| 587 | gpa->lft = cur->rgt;
|
---|
| 588 | cur->rgt = gpa;
|
---|
[a35b458] | 589 |
|
---|
[358ec13] | 590 | /*
|
---|
| 591 | * Repair balances and paternity of
|
---|
| 592 | * children, depending on the balance
|
---|
| 593 | * factor of the grand child (cur).
|
---|
| 594 | */
|
---|
[83a5cba] | 595 | REBALANCE_DELETE_LR();
|
---|
[358ec13] | 596 |
|
---|
| 597 | /*
|
---|
| 598 | * Repair paternity.
|
---|
| 599 | */
|
---|
| 600 | cur->par = gpa->par;
|
---|
| 601 | gpa->par = cur;
|
---|
| 602 | par->par = cur;
|
---|
| 603 |
|
---|
| 604 | if (!repair(t, cur, gpa, cur, &dir,
|
---|
| 605 | false))
|
---|
| 606 | break;
|
---|
| 607 | gpa = cur->par;
|
---|
[1b20da0] | 608 | } else {
|
---|
[358ec13] | 609 | /*
|
---|
| 610 | * LL rotation.
|
---|
| 611 | */
|
---|
| 612 |
|
---|
| 613 | gpa->lft = par->rgt;
|
---|
| 614 | if (par->rgt)
|
---|
| 615 | par->rgt->par = gpa;
|
---|
| 616 | par->rgt = gpa;
|
---|
| 617 | /*
|
---|
| 618 | * Repair paternity.
|
---|
| 619 | */
|
---|
| 620 | par->par = gpa->par;
|
---|
| 621 | gpa->par = par;
|
---|
[a35b458] | 622 |
|
---|
[358ec13] | 623 | if (par->balance == 0) {
|
---|
| 624 | /*
|
---|
| 625 | * The left child of the
|
---|
| 626 | * balanced node is balanced,
|
---|
| 627 | * after LL rotation is done,
|
---|
| 628 | * the whole tree will be
|
---|
| 629 | * balanced.
|
---|
| 630 | */
|
---|
| 631 | par->balance = 1;
|
---|
| 632 | gpa->balance = -1;
|
---|
[a35b458] | 633 |
|
---|
[358ec13] | 634 | (void) repair(t, par, gpa, par,
|
---|
| 635 | NULL, false);
|
---|
| 636 | break;
|
---|
| 637 | } else {
|
---|
| 638 | par->balance = 0;
|
---|
| 639 | gpa->balance = 0;
|
---|
[a35b458] | 640 |
|
---|
[358ec13] | 641 | if (!repair(t, par, gpa, par,
|
---|
| 642 | &dir, false))
|
---|
| 643 | break;
|
---|
| 644 | }
|
---|
| 645 | gpa = par->par;
|
---|
| 646 | }
|
---|
| 647 | } else {
|
---|
| 648 | /*
|
---|
| 649 | * Repair the pointer which pointed to the
|
---|
| 650 | * balanced node. If it was root then balancing
|
---|
| 651 | * is finished. Otherwise continue with the next
|
---|
| 652 | * iteration (parent node).
|
---|
| 653 | */
|
---|
| 654 | if (!repair(t, gpa, gpa, NULL, &dir, true))
|
---|
| 655 | break;
|
---|
| 656 | gpa = gpa->par;
|
---|
| 657 | }
|
---|
| 658 | }
|
---|
| 659 | }
|
---|
| 660 | }
|
---|
| 661 |
|
---|
| 662 |
|
---|
| 663 | /** Delete a node with the smallest key from the AVL tree.
|
---|
| 664 | *
|
---|
| 665 | * @param t AVL tree structure.
|
---|
| 666 | */
|
---|
| 667 | bool avltree_delete_min(avltree_t *t)
|
---|
| 668 | {
|
---|
| 669 | avltree_node_t *node;
|
---|
[a35b458] | 670 |
|
---|
[358ec13] | 671 | /*
|
---|
| 672 | * Start searching for the smallest key in the tree starting in the root
|
---|
| 673 | * node and continue in cycle to the leftmost node in the tree (which
|
---|
| 674 | * must have the smallest key).
|
---|
| 675 | */
|
---|
[a35b458] | 676 |
|
---|
[358ec13] | 677 | node = t->root;
|
---|
| 678 | if (!node)
|
---|
| 679 | return false;
|
---|
[a35b458] | 680 |
|
---|
[358ec13] | 681 | while (node->lft != NULL)
|
---|
| 682 | node = node->lft;
|
---|
[a35b458] | 683 |
|
---|
[1b20da0] | 684 | avltree_delete(t, node);
|
---|
[358ec13] | 685 |
|
---|
| 686 | return true;
|
---|
| 687 | }
|
---|
| 688 |
|
---|
[b76a2217] | 689 | /** Walk a subtree of an AVL tree in-order and apply a supplied walker on each
|
---|
| 690 | * visited node.
|
---|
| 691 | *
|
---|
| 692 | * @param node Node representing the root of an AVL subtree to be
|
---|
| 693 | * walked.
|
---|
| 694 | * @param walker Walker function that will be appliad on each visited
|
---|
| 695 | * node.
|
---|
| 696 | * @param arg Argument for the walker.
|
---|
| 697 | *
|
---|
| 698 | * @return Zero if the walk should stop or non-zero otherwise.
|
---|
| 699 | */
|
---|
| 700 | static bool _avltree_walk(avltree_node_t *node, avltree_walker_t walker,
|
---|
| 701 | void *arg)
|
---|
[d1e9321] | 702 | {
|
---|
[b76a2217] | 703 | if (node->lft) {
|
---|
| 704 | if (!_avltree_walk(node->lft, walker, arg))
|
---|
| 705 | return false;
|
---|
| 706 | }
|
---|
| 707 | if (!walker(node, arg))
|
---|
| 708 | return false;
|
---|
| 709 | if (node->rgt) {
|
---|
| 710 | if (!_avltree_walk(node->rgt, walker, arg))
|
---|
| 711 | return false;
|
---|
| 712 | }
|
---|
| 713 | return true;
|
---|
[d1e9321] | 714 | }
|
---|
| 715 |
|
---|
[b76a2217] | 716 | /** Walk the AVL tree in-order and apply the walker function on each visited
|
---|
| 717 | * node.
|
---|
[d1e9321] | 718 | *
|
---|
| 719 | * @param t AVL tree to be walked.
|
---|
| 720 | * @param walker Walker function that will be called on each visited
|
---|
| 721 | * node.
|
---|
[b76a2217] | 722 | * @param arg Argument for the walker.
|
---|
[d1e9321] | 723 | */
|
---|
[b76a2217] | 724 | void avltree_walk(avltree_t *t, avltree_walker_t walker, void *arg)
|
---|
[d1e9321] | 725 | {
|
---|
[7e36c8d] | 726 | if (t->root)
|
---|
| 727 | _avltree_walk(t->root, walker, arg);
|
---|
[d1e9321] | 728 | }
|
---|
| 729 |
|
---|
[358ec13] | 730 | /** @}
|
---|
| 731 | */
|
---|
| 732 |
|
---|